add a linux_use_debug_fission gyp variable for -gsplit-dwarf

build/common.gypi

 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # IMPORTANT:
 # Please don't directly include this file if you are building via gyp_chromium,
 # since gyp_chromium is automatically forcing its inclusion.
 {
   # Variables expected to be overriden on the GYP command line (-D) or by
   # ~/.gyp/include.gypi.
@@ skipping 735 matching lines @@
 
         # linux_use_gold_flags: whether to use build flags that rely on gold.
         # On by default for x64 Linux.  Temporarily off for ChromeOS as
         # it failed on a buildbot.
         ['OS=="linux" and target_arch=="x64" and chromeos==0', {
           'linux_use_gold_flags%': 1,
         }, {
           'linux_use_gold_flags%': 0,
         }],
 
+        # linux_use_debug_fission: whether to use split DWARF debug info
+        # files. This can reduce link time significantly, but is incompatible
+        # with some utilities such as icecc and ccache. Requires gold and
+        # gcc >= 4.8 or clang.
+        # http://gcc.gnu.org/wiki/DebugFission
+        ['OS=="linux" and target_arch=="x64" and chromeos==0', {

[Mostyn Bramley-Moore, 2014/04/25 21:28:14]

I'm not sure if this must be disabled for chromeos, can someone suggest a
chromeos reviewer?

[dshwang, 2014/04/26 15:21:19]

IMO chromeos is not needed. Above chromeos buildbot failure is due to thread
option, not debug fission.

[Mostyn Bramley-Moore, 2014/04/27 17:59:48]

OK- removed it.

+          'linux_use_debug_fission%': 1,
+        }, {
+          'linux_use_debug_fission%': 0,
+        }],
+
         ['OS=="android" or OS=="ios"', {
           'enable_captive_portal_detection%': 0,
         }, {
           'enable_captive_portal_detection%': 1,
         }],
 
         # Enable Skia UI text drawing incrementally on different platforms.
         # http://crbug.com/105550
         #
         # On Aura, this allows per-tile painting to be used in the browser
@@ skipping 228 matching lines @@
     'enable_extensions%': '<(enable_extensions)',
     'enable_plugin_installation%': '<(enable_plugin_installation)',
     'enable_plugins%': '<(enable_plugins)',
     'enable_session_service%': '<(enable_session_service)',
     'enable_themes%': '<(enable_themes)',
     'enable_autofill_dialog%': '<(enable_autofill_dialog)',
     'enable_background%': '<(enable_background)',
     'linux_use_bundled_gold%': '<(linux_use_bundled_gold)',
     'linux_use_bundled_binutils%': '<(linux_use_bundled_binutils)',
     'linux_use_gold_flags%': '<(linux_use_gold_flags)',
+    'linux_use_debug_fission%': '<(linux_use_debug_fission)',
     'use_canvas_skia%': '<(use_canvas_skia)',
     'test_isolation_mode%': '<(test_isolation_mode)',
     'test_isolation_outdir%': '<(test_isolation_outdir)',
     'test_isolation_fail_on_missing': '<(test_isolation_fail_on_missing)',
     'enable_printing%': '<(enable_printing)',
     'enable_spellcheck%': '<(enable_spellcheck)',
     'enable_google_now%': '<(enable_google_now)',
     'cld_version%': '<(cld_version)',
     'cld2_table_size%': '<(cld2_table_size)',
     'cld2_dynamic%': '<(cld2_dynamic)',
@@ skipping 2174 matching lines @@
               ['OS=="linux" and target_arch=="ia32"', {
                 'ldflags': [
                   '-Wl,--no-as-needed',
                 ],
               }],
               ['debug_unwind_tables==1', {
                 'cflags': ['-funwind-tables'],
               }, {
                 'cflags': ['-fno-unwind-tables', '-fno-asynchronous-unwind-tables'],
               }],
-              # http://gcc.gnu.org/wiki/DebugFission
-              # Requires gold and gcc >= 4.8 or clang.
-              ['linux_use_gold_flags==1 and (clang==1 or gcc_version>=48) and binutils_version>=223', {
+              # TODO(mostynb): shuffle clang/gcc_version/binutils_version
+              # definitions in to the right scope to use them when setting
+              # linux_use_debug_fission, so it can be used here alone.
+              ['linux_use_debug_fission==1 and (clang==1 or gcc_version>=48) and binutils_version>=223', {
                 'cflags': ['-gsplit-dwarf'],
                 'ldflags': ['-Wl,--gdb-index'],
               }],
             ],
           },
           'Release_Base': {
             'variables': {
               'release_optimize%': '2',
               # Binaries become big and gold is unable to perform GC
               # and remove unused sections for some of test targets
@@ skipping 671 matching lines @@
             # the path to gold to the compiler. gyp leaves unspecified what the
             # cwd is when running the compiler, so the normal gyp path-munging
             # fails us. This hack gets the right path.
             'ldflags': [
               '-B<!(cd <(DEPTH) && pwd -P)/<(binutils_dir)',
             ],
           }],
           # Some binutils 2.23 releases may or may not have new dtags enabled,
           # but they are all compatible with --disable-new-dtags,
           # because the new dynamic tags are not created by default.
           ['binutils_version>=223', {

[dshwang, 2014/04/26 15:21:19]

This CL is needed because of this line. We can not use binutils_version=0
workaround anymore.

[Mostyn Bramley-Moore, 2014/04/27 17:59:48]

I'm not sure if it's worth leaving a comment here, but I will add it to the CL
description instead.

             # Newer binutils don't set DT_RPATH unless you disable "new" dtags
             # and the new DT_RUNPATH doesn't work without --no-as-needed flag.
             # FIXME(mithro): Figure out the --as-needed/--no-as-needed flags
             # inside this file to allow usage of --no-as-needed and removal of
             # this flag.
             'ldflags': [
               '-Wl,--disable-new-dtags',
             ],
           }]
         ],
@@ skipping 1313 matching lines @@
     # settings in target dicts.  SYMROOT is a special case, because many other
     # Xcode variables depend on it, including variables such as
     # PROJECT_DERIVED_FILE_DIR.  When a source group corresponding to something
     # like PROJECT_DERIVED_FILE_DIR is added to a project, in order for the
     # files to appear (when present) in the UI as actual files and not red
     # red "missing file" proxies, the correct path to PROJECT_DERIVED_FILE_DIR,
     # and therefore SYMROOT, needs to be set at the project level.
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }